Chances were "missed" to prevent the death of a man after he was examined at a hospital, an inquest has heard.
Simon Willans, 42, died the day after he was sent home from hospital as a consultant did not notice he had blood clots despite having the symptoms, the Caernarfon hearing was told.
A health chief said Mr Willans, of Anglesey, had one set of observations when guidance required two.
She said Mr Willans' previous collapses "should have prompted a rethink."
Betsi Cadwaladr Health Board undertook a serious incident review into the former farm worker's death in January 2016. He died after collapsing at his parents' home on Anglesey.
The trust's medical director Dr Emma Hosking, who chaired the review, said the panel concluded he should not have been discharged on the same day as he went into Ysbyty Gwynedd in Bangor.
"Simon hadn't been fully assessed while on the ambulatory care unit," Dr Hosking told the inquest.
"The initial delay to his admission and incomplete assessment while he was there and poorly documented discharge process added up to some missed opportunities in his care."
Sophie Cartwright, counsel for the Willans family, said there was a failure to diagnose a pulmonary embolism - a blocked blood vessel in the lungs - and deep vein thrombosis.
Consultant Dr Hassan Mohammed had previously told the inquest he did not suspect a pulmonary embolism because Mr Willans said he was not breathless or dizzy.
The inquest has heard procedures at Ysbyty Gwynedd have changed since Mr Willans' death.
Police initially investigated the death but no prosecutions were pursued.
Prof Soloman Almond, brought in by police after the death, said there was a failure by the consultant to bring together "a number of pieces of information" and added Mr Willans's treatment had been "poor".
The inquest has been adjourned. Coroner Dewi Pritchard Jones said the conclusion would be a narrative verdict.